1. Field of the Invention
The present invention relates to a motorized automobile antenna control device which raises an automobile antenna when the power supply of radio receiver is switched "on" and lowers the antenna when the power supply is switched "off".
2. Prior Art
In conventional motorized automobile antenna control devices, while an engine starter is being started the accessory power supply (ACC) is switched "off" so that the load on the battery can be reduced. Accordingly, during this period of time, the radio power supply (RX) is switched "off". As a result, such conventional devices involve the following drawback: i.e., when the engine starter is started, the motorized automobile antenna is automatically lowered. Furthermore, when the engine starter is returned to its original position, the radio power supply is switched "on" so that the antenna is again raised.
In other words, the conventional systems' drawback is that when the engine is started with the motorized antenna in an extended or raised state (e.g., in cases where the engine has unexpectedly stopped, etc.), the antenna undergoes an unnecessary lowering and raising action instead of remaining stationary as would be perfectly accepted. Furthermore, a similar situation can occur in cases where the automobile is started again after listening to the radio with the engine stopped.
Conventionally, the abovementioned drawback has been overcome by using logical operations based upon the ignition (IG) voltage and accessory voltage to determine whether or not the starter is being started and by stopping the operation of the antenna motor while the starter is being started.
In conventional devices, since logical operations are used in order to determine whether or not the starter is being started, three control lines which respectively detect the states of the radio power supply, ignition power supply and accessory power supply are required. Furthermore, the control circuit which determines such logical operations is complicated.